1. Field of the Invention
This invention is generally directed to scalers and curettes which are utilized in periodontics and particularly to scalers and curettes having one or more blades which include inner concave cutting edges which are configured so as to conform with an arc segment portion of a root or crown area of a tooth with such segment being oriented generally perpendicularly to the elongated axis of the tooth. Further, the inner cutting edges are curved so as to create an arc which extends in a plane transverse to the elongated axis of the handle of the instrument so that the cutting edge conforms to the surface of a tooth when the handle is oriented between 45.degree. and 90.degree. with respect to the elongated axis of the tooth. It is preferred that approximately two to three millimeters or more of scaling edge will continuously engage the surface of the tooth depending upon the size of scaler or curette.
In the preferred embodiment of the present invention, the blades of the scalers or curettes include various sizes of blunted end portions, and the scalers incorporate an outer convex surface which is rounded so as not to adversely effect tissue adjacent the portion of the surface of the tooth which is being treated. However, in other embodiments, a pair of spaced generally parallel cutting edges will be provided along the blade of the scalers or curettes.
Although the scalers of the present invention are designed to incorporate blades which have cutting edges which continuously engage an arcuate segment of a tooth or the root of a tooth along a plane which is normal to the elongated axis of the tooth when the handle of the instrument is oriented in a conventional manner at angles of between 45.degree. to 90.degree. with respect to the elongated axis of a tooth, the specific curvature of the blades will be varied depending upon the circumference of a tooth and the size of root being scaled, planed or curettaged. The smallest working ends have a greater degree of curvature and are for use on small root areas such as the lower anterior and upper laterals and bifurcated first bicuspids and upper first molars. The medium or intermediately curved blades are for use on centrals, cuspid and bicuspids, and the least curved or large blades are for use on molars and other large surface areas.
The tip portion of the blades of the scalers in some instances may be curved uniformally with the cutting edges so that the tip will not gouge into tissue surrounding a tooth surface or root being scaled. In addition, the tips will preferably be provided in various sizes. The finest point tip will be utilized for finer bifurcations and narrower spaces; the intermediate blunted tip being utilized for small bifurcations between roots; and the larger rounded tips being utilized in larger areas of scaling between the two roots of lower first molars.
The scalers or curettes of the present invention will generally be designed to provide for both left and right hand curvature with a blade being disposed to the right along one end of the handle of the instrument for scaling one side of a tooth with the blade on the opposite end being oppositely curved so that the same instrument may be utilized for scaling the opposite side of the tooth.
In other separate embodiments, the concave cutting edge of the scaler blades may include one or more projections intermediate their length for scaling slight indentations along the surface areas of some teeth; a saw-toothed like edged surface for scraping hard built-up areas of tartar; or a notched surface for working in roughened or irregular surface locations and also hard built-up areas of tartar. In a further embodiment, the tip of the blade will be curved slightly upwardly to create a spoon effect for scaling all bifurcations and root indentations.
2. History of the Related Art
Periodontal treatment requires the use of a scaler or a curette instrument to remove off the tartar and debris which forms or accumulates on the root surfaces and periodontal pockets. This material acts like a foreign body much as a splinter would in a finger. By removing this material, the tissue adjacent the tooth will become less inflamed and will heal against the root surface or crown portion of the tooth. It has been found that regular scaling promotes healthy teeth and gums and results in many adults being able to retain their natural teeth.
Conventional scalers and curettes have relatively straight scraping or cutting blade portions in relation to the natural curvature of a tooth and also terminate with sharp tips. As conventional scalers and curettes are provided with a straight blade configuration when compared with the cross sectional configuration of a tooth, only a small portion of the working end of the curette or scaler engages a tooth at any one time. Generally, not more than approximately one-tenth of a millimeter of the cutting edge of the scaler or curette actually engages a tooth or the root of the tooth during scaling. Because of this, it is possible to gouge the surface of the tooth along a given portion of the tooth surface especially after repeated scalings as uniform scaling of the surface of the tooth is not provided for.
There have been several scalers designed to more closely conform to the surface characteristics or shapes of teeth. In U.S. Pat. No. 1,220,933 to Bates, dental scalers are disclosed which incorporate blades which are concave so as to conform to the convexity of a root of a tooth. However, the cutting blades are always formed so as to be aligned with the axis of the handles of the instruments. Thus, such scalers had a curvature which is similar to most of today's conventional scalers wherein the blades are curved upwardly toward the axis of the handles of the instruments. In this manner, the curved blades could be used to lift debris from between the roots of teeth and the surrounding gum tissue. However, due to the orientation of the blades and the handles only a small portion of a tooth could be scaled or curettaged with each vertical movement of the blades. Further, with the Bates blade structure, the pointed tip would gouge the surrounding tissue of patient causing pain.
In U.S. Pat. No. 1,605,320 to Bates, a similar scaler or curette is disclosed which includes a blade having cutting edges which are again curved toward the axis of the instrument handle except that a somewhat spiral configuration is given to the cutting edges. With such an instrument, the cutting blades can only be used to scrape larger surface areas of a tooth by rotating the instrument handle into a very angular relationship with respect to the elongated axis of the tooth thereby limiting the efficiency of the depth of treatment relative to a patient's gum tissue. Deeper scaling or curettaging requires the cutting edge to be progressively more vertically oriented and thus results in a smaller surface area being scaled or curettaged with each vertical lifting of the cutting blades relative to a patient's teeth.
Additional prior art references includes U.S. Pat. Nos. 1,605,321 and 1,605,322 to Bates, 2,366,671 to Montelius, 1,497,749 to Diack and 2,002,245 to McDaniel.
In addition to the foregoing, with conventional scalers and curettes, the tips of the blades extend outwardly relative to the surface of the tooth and therefore lacerates or cuts the surrounding tissue when the scaler or curette is being moved vertically relative to the surface of the tooth during scaling. In normal use, a scaler or curette is urged down to the root area of the gingival attachment to the tooth with the scraping or scaling being accomplished by raising or drawing the blade of the instrument vertically toward the top of the tooth. In order to provide a proper angle of contact of the cutting edge with the surface of the tooth, curettes are generally provided with a hooked end portion with the end portion being utilized to trap material being scraped and lift the material as the instrument is drawn upwardly toward the top of the tooth. Unfortunately, the curvature provided on conventional curettes and scalers does not provide for conforming the cutting edge of the scaler with the surface of the tooth. Therefore, only a small portion of the tooth is scraped with each movement of the scaler or curette.
A further problem inherent in conventional scalers and curettes is that they are normally provided with a cutting edge on opposite edges of the blade or working end of the scaler. Therefore, with the scaler engaging the surface of a tooth, there is a sharp cutting edge which extends outwardly into the surrounding tissue. As the scaler or curette is moved, the surrounding tissue is lacerated thereby causing trauma of the local tissue area and also inflicting pain upon the patient.